Imprecise registration equipment such as pointers, which often demand a high degree of computation and/or special equipment, are often replaced by video image sources such as cameras, in order to register a patient and/or a part of a patient's body.
WO 01/59708 A1 discloses a method for the direct registration of two or more two-dimensional optical images to a three-dimensional (3D) image or computer model without prior segmentation of images, including acquiring a plurality of optical images of the object and acquiring three dimensional surface model made up of points on a surface of the object, choosing an initial set of parameters which define the registration between the three dimensional model coordinate system and the optical image coordinate system, measuring the quality of registration using a similarity measure and repeating until a maximum of the similarity measure is found.